Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

The description discloses that only provided fields are changed and omitted fields retain their current values. This adds meaningful behavioral context beyond the annotations, which only indicate non-read-only and non-destructive.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Two concise sentences with the purpose front-loaded and no redundant words. The partial update note is valuable and efficiently stated.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

The tool is simple with a rich schema and output schema. The description covers the essential update behavior and partial update semantics. It lacks explicit usage guidance against siblings, but given the straightforward nature and schema completeness, it is adequately complete for an agent.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the baseline is 3. The description lists the updatable fields and reinforces partial update semantics, but the schema already documents each parameter's behavior in detail, so the description adds limited new parameter-specific value.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the tool updates a shopping list item's name, quantity, and/or category. It uses a specific verb and resource, distinguishing it from sibling tools like add, remove, or buy.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description implies when to use this tool (to modify existing items) but does not explicitly mention alternatives or exclusions. The partial update note gives context but no direct comparison to other shopping list tools.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.